A candy or deep fry thermometer can be checked for accuracy with a pot of water and a stove. The method is simple: place the thermometer in a small pot of water and turn up the heat. As the water begins to boil, the thermometer should read 212°F (100°C).
If the reading is off, the cook has two options. One is to account for the few degrees the thermometer runs hot or cold during cooking. The other is to return it.
The check matters because an inaccurate thermometer can lead to burnt fried chicken or overcooked caramel, according to the source. The test is a basic step that can be done before cooking rather than after a dish has already gone wrong.
The source does not specify how many degrees of variance are acceptable or whether the boiling point changes with altitude. It also does not name any thermometer brands or models. The described method relies on water’s boiling point at 212°F (100°C), which is the standard figure at sea level.
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